Roof jack for ventilating duct



April 17, 1956 R. PRYNE ROOF JACK FOR VENTILATING DUCT Filed Aug. 14,1953 IIM JNVENTOR. RALPH PRyA/E, BY

, United States Patent RalphPryne, Pomona, Calif 'assignorto Pryne &(20., Inc., Pomona, Calif. ,'aicorporation of California ApplicationAugust '14; 1953, .Serial No. 374,332

4"Claims. .(Cl.'9'8-'-11'9) The present invention relates generally toventilating apparatus and equipment and relates more particularly toprotective closure meansfor the open upper end of a ventilating .ductpassing through a roof or the like. Protective closures of this type arecommonly referred to in the trade as roof jacked-and will be so referredto herein, but it will be understood that the term is used withoutintending to limit the invention inany way.

Ventilating fans, or blowers may discharge air from residences andbuildings through an exhaust duct which opens to the atmosphere. Theopen end of this .duct needs to-lbe' protected, not only against'theentry of winds and rain but also convection air .currents "which wouldcreate a back-draft or reverse flowintothe duct when the fan is notoperating. .For this purpose, v.asuitably designed closure meansisprovided on :the. roof-to receive and .cover the open end of.theaexhaustduct, this closure means including .a pivotally mountedshutter which can swing by, gravity to .a position closing the endofathe duct and which can be .opened by the l-Pf6SSLIf6 .of air beingdischarged tothe-atmosphere.

.Because roofs .may .be flat or pitched .atany angle over .aconsiderable range .ofangles, and exhaust ducts of different sizes andshapes are 'found in actual practice, roof .jacks have been of differentsizes and-shapes to fit different .sets of conditions. -Ability'tostandardize ona single design .orsize which, even if notfullyruniversal, wilLfit anumber of-diflerent cond'itions, will resultin :a cheaper, moresatisfactoryarticle. t

It is a general object of my invention to improve the effectiveness of.the-aoperation of closure :means of this type .at :the end of anexhaust duct. a It is .alsoa general-objectofmy invention toprovide anew and improved design [for a roof jack which adapts a vjack of .asingle standardized sizetos-all roofs within the range of :slopesusually encountered, vas well as a flat roof, and :a-considerable'varietyvof sizeszaofwexhaust ducts. 7. his also ;an object *of myinvention to :provide .an improved design for a roof jack ain-which windblowing into ?the outlet-op'eningis deflected to exert a force-on theshutter .tendingtto close lthe'shutter and thereby keep out the Wind. rp

It vis a further objectof :my invention to provide .an improved designfor :a roof jack in which the aoutgoing stream of air is deflectedsmoothly :and continuously towards then-outlet of rthe jack so that :the:air :stream .flowsthrough the roof =jack'with atminimum:ofiiresistance.

The above objects are obtained .in :a closure mean's embodyingrny'dnvention having a planar base :flange and wall means :risingupwardly from the flange around the sides of an inlet "opening definedbyzthe2flange. The wall means includes a pair of parallel side :v'valls,a front wall that slopes upwardly and rearwardly, ,and a rear .wallthat-slopes aupwardly and forwardly. Inside the .jack the walls define athroat of .materiallywlesser .area Qthan the .inletopening; .and.-a..shut ter is ,mounted at the throat to swing by gravity towards anormal closed 2 position. A portion of the rearv wall extends forwardlyover the sloping'front wall and, together with portions of thesidewalls, forms a hood over the shutter and also defines a downwardlyfacing air outlet opening.

In a preferred embodiment, the shutter is mounted on a removable framewhich ,is held in place at the throat by engagement with thevarious-walls of the closure means. This frame carries a baffle alongits forward side toshield the forward edgelof'the shutter from air currents which might .tendto open it andblow'past the shutter.

How the above objects and advantages of my invention, as well as othersnot specifically referred to herein, are attained will be more readilyunderstood by reference to the following description and to the annexeddrawings, in which:

Fig. Us a. perspective viewof a roof jack embodying my invention;

Fig. 2 is an enlarged vertical section through my improved roof jackshowing it'mounted on-a flat roof;

Fig. 3 is a fragmentaryhorizontal section on lin'e 3'3 of Fig. '2;

Fig. 4 is a fragmentarvsection on line 4-4 of Fig. 2; and 1 Fig.S'isaside elevation-atreduced scale showing the roof jack installed on asloping roof.

.Referring now to the 1 drawings, there is shown in Fig. 1 a roof jackas it appears by itself; and itis shown installed on a flat roof in Fig.2 or on a sloping roof inFig. 5. 'Theroofjack has 'aflator=planar flange-10 atits base by which the-jackis fastened to roof -12 in an ait-tightand Water-tight manner. Details of this connection to the roof areconventional and notpart of this invention, so are-not shown. Thejack ismounted on top oftheroof over the-open-upper'endof exhaust duct '14which normally is running vertically 'wherexit passes through the roof.Air forcedthroughduct 1 4 by-a-famnot shown, isexhausted to theatmosphere after passing through the .roof jack. At the level of 'baseflange :10 :is inlet opening 15 which ispreferably-"rectangular,-typically beingsquare. The flangeextends'outwardly from 1and='entirely aroundthe inlet opening inorder-to define the' opening The end of duct 14: projects intothe-interior of the roof jack through inlet opening 15, as may be seenin-Figs.:2 andS.

:The main body 16 of the roof jack is formed "by wallmeans' :extendingupwardly from flange 10 around the edges of inletopeninglS. The wallmeans'omprises two' sidewalls "18, a front wall'20, anda'rearwall 2'2.Thetwowside Walls areflatmembers that are-preferably parallel itoeachother and perpendicular to the base flange. Frontwall20 is also flatover m'o'st-ofits extent and slopes .rearwardly'and upwardly. The frontwall makes an angle'of about 35 with the plane of flange 10 isapre'ferredform of my invention, but this angle may be variedby atleastl0 either'way and still obtain the advantages of myinvention. At theupper endof the'front wall is an upstanding'flange 20a extendingentirely across .the "front Wall between the two side walls.

Rear wall 22rises perpendicularly from flange 10 for a short distanceand then curves smoothly forward so that portion 221: of it overhangsthe front wall "like a hood. The side'walls rise above front wall 2t)and join the overhanging portion of the rear Wall; and'there is formedbythe four walls an air outlet opening of rectangular shape at '24 abovethe sloping front wall. Exhausted air leaves the roof jack through thisopening.

Thatside .of theroof jack towards which theexhaustor outlet opening24'is directed has been arbitrarilyde'signated as the front ,side oftheiroof jack; andaccor'dingly theoppositesideis termed thefrearside.

The space inside housing 16 tapers upwardly to a comparativelyrestricted opening at throat 25 at the upper end of the front wall.Throat 25 is rectangular in outline and may be considered to be boundedat each side by one of the four walls of housing 16. At this throat islocated shutter 26 which shuts by gravity to close the throat tobackdrafts. Closing the throat keeps rain, cold air or wind, fromflowing down exhaust duct 14. At the same time, the shutter is made solight in weight that the normal pressure of the exhaust air streamagainst the inner or under side of the shutter opens it easily, asindicated in the dot-dash position of Figs. 2 and 5.

As a means for supporting the shutter in place, it is preferred toprovide at throat 25 an open rectangular frame 27 which fits snuglywithin the throat and engages all the housing walls. It is preferred tosurround the frame with a strip 23 of felt or the like to make the framefit tightly enough to prevent air from passing between the frame and thehousing. Frame 27 consists of narrow angular members which extend aroundthe four sides of a central opening. The frame members can be seen inFigs. 2 and 4, and may be padded on the outside with a layer of felt 29that engages the margins of shutter 26 to effect an air-tight seal withthe shutter.

Shutter 26 is pivoted at 28 on frame 27 to swing about a horizontalaxis. This axis is located closely adjacent to rear wall 22 and isalways above and rearward of the bottom edge of the shutter and also ofthe lower side of the frame, for all ordinary inclinations of baseflange 10. As a consequence, the shutter is always urged by gravitytoward the closed position. This is true when a roof jack is mounted ona flat roof as in Fig. 2, or on a pitched roof as in Fig. 5 because theshutter is normally disposed at about the same slope as the front walls.Roofs seldom exceed a slope of 30; and the proportions shown permit theshutter to close normally for any pitch up to and beyond 30. Shutter 26closes in a normal manner even when the roof is pitched as deeply as 45because, assuming the shutter to be at 35 to the flange, as is the frontwall, the shutter then makes an angle of 80 with the horizontal. Thefurther the shutter is opened, the greater the force tending to closeit.

Frame 27 may be held in place in any suitable manner. Here the frame hason its rearward side a flange 27:: which is held between the rear walland a resilient clip 30 fastened to the inside face of wall 22. Clip 30is an elongated strip of metal which is attached to the rear wall of thehousing along its lower edge, as by spot welding, to form an air-tightjoint. The strip extends across substantially the full width of wall 22,as may be seen in Fig. 4. Flange 27a on the frame is inclined at theproper angle to lie against this spring clip when it is inserted betweenthe elip and the housing wall, as shown in Fig. 2. Light pressure of thetwo members against each other forms an air-tight joint at this point.The resilient nature of strip 30 allows it to maintain this sealingcontact with the frame while at the same time moving toward or away fromthe rear wall to accommodate minor variations in the front-to-reardimension of frame 27.

Extending entirely across the side of this frame is another dependingflange 27b which is parallel to and in engagement with flange 20a of thefront wall. Contact between these two flanges maintains an air-tightconnection at this point; and the two flanges may be held together byany suitable means, as for example by metal screw 31.

Also mounted on the lower edge of frame 27 is baffle 32 which extendsentirely across the frame. This angular baflle member shields the edgeof the shutter from air currents which enter the roof jack throughoutlet opening 24 and might otherwise blow under the edge of shutter 26and between shutter and frame 27 Such entering air currents are directedupwardly away from the edge of the shutter by the battle. In general,gusts of wind and the like blowing into opening 24 strike against theunderside of curved wall 22a of the housing and are then directed 4downwardly against the outside face of shutte direction to more firmlyclose the shutter.

It is preferable to close opening 24 against the entry of birds byproviding screen 34 at the opening, which screen may be of relativelylarge mesh. Cut to the same size as the outlet opening in the housing,the screen may be pushed into place, and is then held frictionally. Anarrow metal clip 35 attached to the housing at one end may be then bentinto a U-shape to engage the under side of the screen and hold itagainst dropping downwardly.

Rectangular inlet 15 is considerably larger than throat 25. Althoughboth openings have one dimension in common, since they both extend thefull distance between side walls 18, in the other dimension inlet 15 istwo or more times the size of the throat. This is done in order toaccommodate the roof jack to exhaust ducts of various sizes and shapes,irrespective of whether or not the base of the jack is sloped withrespect to the duct because it is mounted on a pitched roof. A largevariety of sizes and shapes of exhaust ducts are commonly encountered.An oblong duct approximately ten inches by three inches is usedfrequently in interior partition walls. A six inch square duct is alsofrequently encountered while in round ducts diameters are as large assix to eight inches. Since the largest of these dimensions is teninches, the inlet opening 15 is preferably made slightly larger than teninches in each dimension. This has the further advantage that a squareor round duct up to eight inches can also be easily accommodated, evenon a steeply pitched roof. This situation is shown in Fig. 5 where duct14a represents a typical round duct.

On a-fiat roof, the opening required to receive the end of the exhaustduct has the same dimensions as the exhaust duct itself. However, on asloping roof, the inclination of the plane of the inlet opening requiresthat it have a dimension from front to rear considerably greater thanthe corresponding dimension of the exhaust duct. At the same time, thenet area at the throat need only be of approximately the same magnitudeas the cross sectional area of the duct so that the throat can beconsiderably smaller than the area of the inlet opening. This being thecase, the forward wall of the roof jack is sloped upwardly andrearwardly to give an upwardly tapered shape to the space within thehousing. It will be noted that at its point of closest approach to therear wall, there is still suificient space between the rear wall and thefront wall to allow the duct to project into the interior of the housingfor at least a short distance.

The air exhausted from the end of the duct encounters the curvedunderside of wall 22a and is directed over a smoothly curved path to theoutlet from the roof jack which faces downwardly in order to protect itfrom wind and rain. Actually, the direction of the exhaust stream may bechanged as much as from the direction it is flowing at the time itleavesthe exhaust duct. At the same time, this change in direction is madewithoutcreating any pockets within the housing in which the air collectsor which would offer resistance to streamline flow.

The roof jack is normally mounted with the exhaust duct as close to therear wall as is practical in order that the air is directed as much aspossible directly toward and against the under side of shutter 26. Inthis position the full energy of the outwardly moving air stream isavailable to open the shutter.

From the above description, it will be seen that various changes in theproportion or shaping of parts may be made without departing from thespirit and scope of my invention; and accordingly it is to be understoodthat the above description is considered as being illustrative of,rather than limitative upon, the appended claims.

I claim:

1. A closure means for an exhaust duct or the like venting through aroof, comprising; a planar flange for attachment to the roof with anair-tight seal and extending around a rectangular air inlet opening tothe closure r26ina means adapted to receive an end of the exhaust duct;Wall means rising upwardly from said flange around the inlet openingtherein, said wail means including a pair of parallel side walls, arearwardly and upwardly sloping front wall, and a rear wall extendingupwardly and forwardly,

said wall means defining at the upper end of the front wall arectangular throat that is above and has not more than one-half thefront-to-rear dimension of the inlet opening; a resilient clip fastenedat its lower edge to the inside face of the rear wall; an open frame atthe throat and having at its upper edge a flange received between theback wall and said resilient clip; cooperating means on the frame and onthe upper end of the front wall engaging each other to position theframe; and a shutter pivotally mounted at its top edge to the upper sideof the frame and gravity biased to normally close the opening in theframe to prevent back-draft into the duct.

2. A closure means for an exhaust duct or the like projecting through aroof, comprising: a planar flange for attachment to the roof andextending around and defining a rectangular inlet opening comprisingsubstantially the entire underside of the closure means and adapted toreceive the upper end of the exhaust duct; wall means connected to andrising from the flange at the sides of the inlet opening, said wallmeans including a pair of parallel side walls, a rear wall having anupwardly and a forwardly extending portion, and an upwardly andrearwardly sloping front wall that is disposed at an acute anglerelative to the planar flange and terminates beneath the forwardlyextending portion of the rear wall at a position spaced rearwardly fromthe front end of the rear wall to form with said rear wall a rectangularthroat which is coextensive with the inlet opening between the parallelside walls, but has about one-half the front-to-rear dimension of theinlet opening, and said front wall and the front end of the rear walldefining with the side walls an outlet opening disposed above thesloping front wall; and shutter means at the throat.

3. A closure means as in claim 2 in which the front wall slopes at anangle of about 35 with respect to the plane of said planar flange.

4. A closure means for an exhaust duct or the like venting through aroof, comprising; a planar flange for attachment to the roof with anairtight seal and extending around a rectangular air inlet opening tothe closure means adapted to receive an end of the exhaust duct; wallmeans rising upwardly from said flange around the inlet opening therein,said wall means including a pair of parallel, upwardly extending sidewalls, a sloping front wall that extends upwardly and rearwardly makingan acute angle with the planar flange, and a rear wall having anupwardly extending lower portion and a forwardly extending upper portionthat extends over and is spaced above the sloping front wall, said wallmeans defining at the upper end of the front wall a rectangular throatthat is above and has substantially one half the front to rear dimensionof the inlet opening, said forwardly extending portion of the rear walljoining the side walls at their upper ends to form a hood over thethroat and, in cooperation with the sloping front wall, a downwardlyfacing outlet opening above the front wall.

References Cited in the file of this patent UNITED STATES PATENTS203,447 Handover May 7, 1878 992,849 Chalke May 23, 1911 1,592,841Ansell July 20, 1926 2,184,110 Anderson Dec. 19, 1939 2,300,842 LeslieNov. 3, 1942 2,565,131 Johnson Aug. 21, 1951

